Olfactory Dysfunction in Patients With Acetylcholine-Receptor-Antibody-Positive Myasthenia Gravis

Abstract

Background and Purpose Myasthenia gravis (MG) is an antibody-mediated disease characterized by fluctuating muscle weakness and fatigue due to impaired neuromuscular junction transmission. Although primarily considered a motor dysfunction disorder, there is emerging evidence that MG can also present with nonmotor symptoms, including olfactory impairment. However, the prevalence and clinical relevance of olfactory dysfunction in MG remain poorly understood. This study compared olfactory function between MG patients and healthy controls with the aim of identifying clinical factors associated with olfactory impairment in MG. Methods Acetylcholine receptor (AChR)-antibody-positive MG patients and healthy controls were recruited from a single-center outpatient clinic. Olfactory function was assessed using the KVSS II (Korean version of the Sniffin' Sticks II) test, comprising odor threshold, discrimination, and identification subtests. We compared olfactory function and clinical factors between MG patients and healthy controls after adjusting and matching for age and sex. Results This study enrolled 51 MG patients and 43 healthy controls. Logistic regression analyses revealed that the MG patients had a significantly increased risk of olfactory dysfunction (odds ratio=3.6, 95% confidence interval=1.4-9.1, p=0.008), which remained after adjusting for age and sex. Among the MG patients, those with olfactory dysfunction were older (p=0.002) and had lower AChR antibody titers (p=0.029). Conclusions Olfactory dysfunction was significantly more prevalent in the MG patients than in the healthy controls. These findings highlight the need for further research into the underlying mechanisms and potential clinical implications of olfactory impairment in MG.